"Signed, Sealed, Delivered," starring Eric Mabius and Kristin Booth, tells the inspiring story of a group of postal detectives whose mission is to deliver letters and packages from the past, which arrive miraculously when they are needed most.

The Denver native is part of network television history while standing proudly apart from it. Her spiritually uplifting “Touched by an Angel” was a hit on CBS for nine seasons but was always out of step with the shooting, maiming, exploding, killing trends in prime time.

Now, after an absence of 10 years, Williamson returns to TV with a new series in a different venue: cable.

The values remain the same.

“Signed, Sealed, Delivered” premieres on the Hallmark Channel as a movie Oct. 12 at 7 p.m., and is expected to become a series (the network has requested three more scripts). This marks Hallmark’s third scripted series.

The story concerns a crew of four postal detectives in the dead-letter office. Their mission is to deliver letters and packages from the past, letters and packages that save lives, solve crimes, reunite old loves, and change futures, arriving late but, “miraculously on time, when they are needed most.”

Imagine an old-fashioned guy whose workplace is suddenly invaded by a thoroughly modern young woman. He is all about letter-writing and the written word; she lives on the Internet.

There’s a possibility of romance between the leading characters, Oliver and Shane, played by Eric Mabius (“Ugly Betty”) and Kristin Booth (“The Kennedys”).

Williamson insists the thrust is not a knock on technophiles, but she does worry about people losing themselves in the digital world.

“They may kill me for saying this,” Williamson said, “but it’s an old-fashioned romance that celebrates the written word and the thoughtfully composed letter we don’t send anymore.”

The story is set in Denver, but shot in Vancouver. Williamson wrote much of the script in a cabin near Nederland that’s been in the family since 1942.

“I wanted to go back and write it around my family. Denver’s still my family. I grew up a block away from Washington Park on South Gilpin Street. (She’s a South High grad). A great deal of the story takes place in Wash Park.”

Williamson included a few “winks” to hometown viewers, notably in newscasts within the drama, when a heat wave forces Nederland to cancel their planned festivities. (Puzzled out-of-towners are directed to the Nederland Chamber of Commerce explanation of Frozen Dead Guy Day.)

And when a dead-letter detective’s job is in jeopardy, Williamson sneaks in another favorite local reference: “I could end up selling stamps in Pueblo, Meeker or East Tincup.” (Williamson’s father was acquainted with radio legend Pete Smythe, who created the fictional Old West town in his imagination.)

While Williamson champions upbeat content, her other goal is to bring strong production values, quality, “and the challenging issues we addressed on ‘Touched by an Angel’ and ‘Promised Land’ to a Hallmark audience.”

For a writer-producer working outside the typical network wheelhouse, the boom in streaming services like Netflix and Hulu now offering original programming is “very tempting,” she allowed. “I would love to be part of that. Being able to choose your entertainment without having to fight through stuff you don’t want to see is particularly important to parents.” Case in point: her daughter accidentally stumbled onto a Quentin Tarantino film while trying to find a movie about horses.

“I had to talk her down.”

Since “Touched,” Williamson has written and performed a one-woman show and contributed a blog to beliefnet.com, which included her in a list of “The 12 Most Powerful Christians in Hollywood,” right up there with Kristin Chenoweth, Mel Gibson and Phil Anschutz.

With cutting-edge adult dramas winning awards on cable networks, and low-cost reality shows proliferating on the broadcast networks, Williamson said, “I realized I needed to go to Hallmark. My brand and their brand seemed destined for each other.”

After all, she observes, nobody is more invested in sending letters through the mail than the company rooted in greeting cards.